Since the inception of ion chromatography (U.S. Pat. No. 3,920,397), the basic technology for the anion-exchanger used in the analytical column for anion determination has not changed. Solid microparticles of anion-exchanger are agglomerated with macroparticles of surface sulfonated or fully sulfonated styrene divinylbenzene copolymer to produce a low capacity "pellicular type" anion-exchanger (U.S. Pat. No. 4,101,460).
Improvements within this basic technology came with the use of monodisperse anion-exchange latex rather than the previously used ground anion-exchange resins (as described in the '460 patent), and by performing an agglomeration step in a polyvalent salt solution (U.S. Pat. No. 4,119,580). The use of monodisperse anion-exchange latex eliminated the problem of refining ground ion-exchange resin to obtain the desired size range, while agglomerating in a polyvalent salt solution resulted in a reproducible and dense deposition of microparticles due to the resulting suppression of the anionic repulsion forces between the microparticles.
A further improvement is disclosed by U.S. Pat. No. 4,383,047 wherein the use of smaller diameter latex microparticles is prescribed. Anion-exchangers of this type achieve a performance level in which baseline separation of fluoride, chloride, nitrite, phosphate, bromide, nitrate, and sulfate ions is completed in about 6 minutes (illustrated by the chromatogram in FIG. 3 of the '047 patent).
Throughout these developments in the technology the packing compositions have been limited to eluent insoluble resins for both the agglomerated and substrate components. There has not been any suggestion that other types of components could be useful or practicable.